Headstone for an Apocalypse

By PETER BRANNEN

August 16, 2013

SHROUDED by foliage and separated from the city by the Hudson River, the looming cliffs of the Palisades mean little more to most New Yorkers than a pleasant view from the West Side Highway. But these titanic ramparts of ancient basalt are also monuments to an apocalypse.

The cliffs were once underground channels of molten rock that fed widespread volcanic eruptions 200 million years ago as the supercontinent Pangaea pulled apart at the seams. The eruptions covered more than four million square miles with basalt lava and belched vast amounts of carbon dioxide and sulfur into the atmosphere. Brief volcanic winters followed, but the eruptions also set off an ocean-acidifying, global-warming catastrophe that wiped out three-quarters of life on earth. This was the end-Triassic extinction, which cleared the way for the dinosaurs and their domination of the planet for the next 136 million years, before a giant asteroid struck Mexico and ended their reign.

This spring, a team of researchers from Columbia University and the Massachusetts Institute of Technologypublished a paper in the journal Science connecting these eruptions — which took place in four pulses over 600,000 years — with this global near-death experience, one of five major extinctions over the last 540 million years.

Paul E. Olsen, a paleontologist at Columbia and one of the study’s co-authors, recently took me on a tour of the Palisades. Before we left, he showed me a fossil that he and his 12-year-old son found on a beach in Haverstraw, N.Y., along the Hudson — the imprint of a clumsy-looking five-knuckled foot. It was made by a species of crocodilian reptile, a rauisuchian, the dominant predator before the volcanic cataclysm.

“You can find fish and reptile fossils here by the hundreds, were the rock not so hard,” he said as we hiked to a point up from the Ross Dock Picnic Area, just north of the George Washington Bridge in Fort Lee, N.J., where the base of the Palisades meets older sedimentary rock.

Victo Ngai

The area was once part of a huge tropical rift valley created as the continent cleaved apart. The patterns of colors on these sedimentary rocks — from black and thinly striated to red-brown — are markers of an ancient lake that alternated from deep to shallow in 20,000-year cycles controlled by the wobble of the earth’s axis and the amount of sunlight hitting the planet. Professor Olsen discovered that the first wave of the extinction happened within just a single sedimentary layer, in less than 20,000 years, as atmospheric carbon dioxide likely doubled from the eruptions, sending global temperatures soaring by 3 degrees Celsius or more.

We dodged a car rushing along a park road as we continued our hike. Behind us, through a thicket of bittersweet and porcelainberry, I spotted the outline of New York City. We’re living in the Anthropocene, the newly named geologic epoch dominated by man. The city is a churning symbol of this new age, a metabolic node of the human superorganism.

Some scientists believe we are now in the midst of another great extinction, driven not by natural events but by the activities of man: hunting, habitat destruction, the introduction of invasive species and pollution, which has drastically altered the thin glaze of life-supporting chemistry that coats the earth. By some estimates, perhaps close to 30,000 species of plants and animals go extinct every year. Whole ecosystems, like coral reefs, which went virtually extinct in the end-Triassic extinction, are now facing worldwide collapse again.

A World Bank report last fall warned that “present emission trends put the world plausibly on a path toward 4 degrees Celsius warming within the century.” The surface waters of the carbon-dioxide absorbing oceans have already become 30 percent more acidic since the start of the Industrial Revolution.

“In terms of global warming and ocean acidification,” Professor Olsen said, the rate of change during the end-Triassic extinction “was comparable to what we’re doing today.”

As I looked up the cliffs I wondered what we would leave to the ages. If catastrophe strikes, would future geologists find evidence of New York, a marker for our time, just as the Palisades have survived as a tombstone for another era?